Cathode ray tube protective front panel device



8- 1964 A. T. MONACO ETAL 3,146,305

CATHODE RAY TUBE PROTECTIVE FRONT PANEL DEVICE Filed Dec. 14. 1981INVENTOR. Anthony T. Monaco Richard S. Sobie 14% (M United States PatentOffice 3,146,305 Patented Aug. 25, 1964 3,146,305 CATHODE RAY TUBEPROTECTIVE FRONT PANEL DEVICE Anthony T. Monaco, Skokie, and Richard S.Sobie, Glen Ellyn, Ill., assignors to Motorola, Inc., Chicago, 11].,

a corporation of Illinois Filed Dec. 14, 1961, Ser. No. 159,315 3Claims. (Cl. 178-732) This invention relates generally to cathode raytubes and more particularly to a protective front panel for a cathoderay tube.

Many devices, such as Oscilloscopes and television receivers employcathode ray tubes, the proper operation of which requires evacuation ofthe interior of the tubes. Because of the virtual vacuum inside thesetubes, rupture of the glass shell may cause a sudden and violentshattering of the tube with resultant flying glass.

To protect a viewer from injury in the event of such an occurrence,these devices are generally provided with a protective cover oftransparent material over the face of the tube. One method of doing thisis to bond a transparent cover directly to the outer surface of theoathode ray tube screen. Such procedure however, is expensive andnecessitates replacement of the protective cover every time the picturetube is replaced. Another method of guarding against implosion forces isto provide a transparent cover mounted over the face of the cathode raytube and separated therefrom to leave a space between. Because of theviolence of implosion forces, such an arrangement has required the useof relatively thick glass or other transparent material, which may beexpensive. Furthermore, an effective seal must be provided to preventmoisture and dust from entering the space between the screen and thecathode ray tube which might cause deterioration of viewing quality.

An object of this invention is to provide an implosion guard for acathode ray tube which is low in cost.

Another object of this invention is to provide an improved implosionguard for a cathode ray tube which is readily separable from the tube.

It is a further object of this invention to provide a removableimplosion guard for a cathode ray tube, with an effective seal againstthe entrance of moisture and dust into the dead air space between theimplosion guard and the cathode ray tube.

Another object of this invention is to permit the use of a relativelythin protective transparent panel for a cathode ray tube.

A feature of the invention is the provision of a mounting gasket of dualtubular construction surrounding the periphery of a transparentimplosion panel for effectively floating the panel over the viewing faceof a cathode ray tube.

A further feature of the invention is the provision in the firstmentioned feature of a resiliently mounted flexible frame member forholding the gasket against the periphery of the face of the picture tubeto aid absorption of implosion forces.

Another feature of the invention is the provision in the above-mentionedgasket of serrations along the bearing surfaces of the gasket tofacilitate the gripping and sealing functions.

In the drawing:

FIG. 1 is a perspective view of a cathode ray tube and support frameutilizing the invention;

FIG. 2 is a perspective view of a television receiver in which theinvention may be used;

FIG. 3 is a cross-sectional view of the gasket as shown in FIG. 4, butin unassembled relationship; and

FIG. 4 is a sectional view along the line 4-4 of FIG. 2.

In brief the invention includes a gasket of resilient material,preferably polyvinyl chloride, stretched to fit about the outer edge ofa glass protective panel. The gasket is held on the panel by means of achannel provided in the gasket which receives the edge of the paneltherein. The gasket contains two hollow tubular portions, continuousthroughout, which are formed on either side of the channel. The paneland gasket are held over the viewing face of a cathode ray tube by meansof a flexible frame and resilient mounting. The frame fits over thegasket applying pressure thereto so that the gasket provides aneffective seal for the space between the transparent panel and theviewing face of the picture tube. When the gasket and panel are heldagainst the tube in this manner, one of the tubular portions is disposedbetween the transparent panel and the viewing face of the tube, and theother tubular portion is disposed between the frame and the transparentpanel. Thus, the gasket provides a cushion of air on either side of thetransparent pane, effectively floating the panel in front of the tube toform a resilient implosion guard that will absorb implosion forces whileat the same time reduce the required thickness of the glass panel.

Referring to FIG. 1, a cathode ray tube 11 is mounted on a chassis frame13 by means of a mounting assembly 15. Chassis frame 13 may have mountedthereon a chassis containing various electrical circuit elements for theapparatus in which tube 11 is used. Mounting assembly 15 includes astrap or support member 17, on which the bottom of tube 11 bears. Alsoincluded in mounting assembly 15 is side member 21 which is clipped toopenings 23 in support member 17 by tabs 25. Side member 21 is securedto chassis frame 13 by screws 26, the opposite side of assembly 15 beingidentical. A band or strap 27 extends across the top of tube 11 andsecures the tube against support member 17 by means of screw 29extending through bearing portion 31 on strap 27, and threaded intotapped bracket 33 on side member 21. An identical arrangement is used onthe opposite side of tube 11.

With this arrangement, tube 11 is secured to chassis frame 13 asfollows. The tube is placed so that the bottom rests on support member17, which is suspended from side member 21 by tabs 25 clipped inopenings 23. Side member 21 is fastened to chassis frame 13, as is thecorresponding member on the opposite side of tube 11. Thus, tube 11 isat this point suspended from chassis frame 13. Screw 29, and itsopposite, are then tightened, causing strap 27 to force tube 11 down onsupport member 17, placing the viewing face of tube 11 in compressionfor added strength. Finally, support member 17 is secured to chassisframe 13 with a threaded fastener through bracket 19, and with anidentical means on the opposite side.

The general appearance of tube 11 as viewed from the outside of atypical device in which it is used, e.g. a television receiver, isdepicted in FIG. 2. Receiver cabinet 35 has on the exterior thereof anescutcheon plate 36, controls 37, and a grill cloth covered opening 39for a loudspeaker. T.e screen of tube 11 is visible through transparentimplosion panel 41, with the viewing face being framed by a bezel 42..As may be seen from this view, it is necessary that implosion panel 41be sufliciently strong to withstand implosion forces to reduce thelikelihood of a viewer being struck by flying glass. Panel 41 may bemade of tempered glass curved to follow the contour of the viewing faceof tube 11.

Implosion panel 41 is mounted over the face of cathode ray tube 11 bymeans of a flexible frame 43. Flexibility of frame 43 aids in providinga cushioning effect for implosion panel 41 in the event of implosion oftube 11. Frame 43 is secured on both sides to chassis frame 13 bybracket portions 45. Frame 43 is secured to mounting assembly 15 at thetop thereof by means of a resilient spring 47 captured in clip 49 whichis attached to frame 43, and also captured behind stop portions 51 onthe mounting assembly. The bottom is resiliently mounted in identicalfashion. Such an arrangement furthermore prevents the center of frame 43from flexing outwardly to break the seal of the gasket, describedsubsequently.

Implosion panel 41 is effectively float mounted by means of gasket 53.Gasket 53, the cross-section of which is best seen in FIG. 3, iscomprised of two hollow tubular portions 55 and 57, the former being thelarger of the two. Connecting tubular portions 55 and 57 is web portion59. The arrangement of the various portions is such as to form a channel61 therebetween.

Gasket 53 is stretched and fitted around the periphery of the shapedpanel 41. The larger tubular portion 55 is arranged on the interior sideof the panel 41, so that when panel 41 is placed against the viewingface of the cathode ray tube 11, the larger tubular portion 55 of gasket53 will bear against the viewing face of tube 11, cushioning panel 41.against it and suspending panel 41 a short distance from the viewingsurface of tube 11 to leave a space 66 therebetween. Physical contact ofpanel 41 with the viewing face of tube 11 is avoided so that directtransmission of implosion forces from the tube to the panel is avoided.

The smaller tubular portion 57 of gasket 53 is arranged on the outsideof panel 41 to isolate the panel from flexible frame 43. As seen in FIG.4, when flexible frame 43 is placed in position to secure panel 41 overthe face of tube 11, gasket 53 is compressed compliantly to form acushion for panel 41 and in addition to provide an effective seal forspace 66. Such a seal is necessary to prevent dust and moisture fromentering the space and causing cloudiness to obscure viewing. Serrationsor longitudinal ridges 63 provided along appropriate surfaces of gasket53 (see also FIG. 3) facilitate the gripping of panel 41 and tube 11 bythe gasket, and also aid in maintaining the sealing of the dead space66. As frame 43 is mounted, the hump on the top of tubular portion 55 isrolled out flat along the top of tube 11 to isolate the tube from theframe.

From FIG. 4 it may readily be seen that hollow tubular portions 55 and57 of gasket 53 enable panel 41 to be effectively floated from the tube11 on a cushion of air. This floating effect permits the use of muchthinner glass in the implosion panel while still maintaining theequivalent implosion protection of conventional devices.

Gasket 53 is preferably made of a substance called polyvinyl chloridewhich provides the economical optimum of strength and flexibility. Inaddition, it is further desirable that the polyvinyl chloride substancebe of low plasticizer content to avoid emission of gasses into space 66as temperatures increase during operation of the device. This is toreduce the likehood of the gases fogging to impair viewing quality. Tofurther reduce this possibility space 65 is filled with dry nitrogen gasunder pressure during assembly just prior to sealing. The introductionof a relatively inert gas such as nitrogen into space 66 forces out theair occupying the space, along with any moisture contained therein.Furthermore, such a gas will not cause any problems due to reaction withthe materials surrounding the space.

It may therefore be seen that the invention provides an effective guardagainst implosion forces which requires relatively less thickness of theimplosion panel due to resiliency of the mounting arrangement. Inaddition, the air space between the cathode ray tube and the implosionpanel is effectively sealed against moisture and dust.

We claim:

1. An implosion guard for a cathode ray tube including in combination, atransparent panel for covering the viewing face of the tube, a mountinggasket of compressible material surrounding the periphery of said panel,said gasket having a channel formed therein to receive the edge of saidpanel, a structure for supporting the tube in view ing position, aflexible frame engaging said gasket, first means rigidly mounting saidframe at both sides thereof to said structure, and second meansresiliently mounting said frame at the top and bottom thereof to saidstructure so that said gasket is pressed against the viewing face of thetube, thereby suspending said panel a short distance in front of theviewing face of the tube to seal the region between said face and saidpanel from foreign matter and to form a resilient guard for absorbingimplosion forces.

2. The combination of claim 1 wherein a dry, inert gas is introduced inthe region between said face and said panel.

3. An implosion guard for a cathode ray tube including in combination, atransparent panel for covering the viewing face of the tube, a mountinggasket of compressible material surrounding the periphery of said panel,said gasket having a channel formed therein to receive the edge of saidpanel, a structure for supporting the tube in viewing position, aflexible frame engaging said gasket, said frame having a bracket portionon each side thereof secured to said structure, said frame furtherhaving a hook portion at the top and bottom thereof, a pair ofprojections on the top and bottom of said structure, and a pair ofelongated resilient members having their ends engaging said projectionson the opposite side thereof from said frame, said resilient membersfurther being displaced in the center thereof to be captured in saidhook portion so that said frame is resiliently mounted at the top andbottom thereof to said structure, said frame compressing said gasketagainst the viewing face of the tube so that said panel is suspended ashort distance in front of the viewing face of the tube thereby forminga seal and a resilient guard for absorbing implosion forces.

References Cited in the file of this patent UNITED STATES PATENTS2,456,399 Gethmann Dec. 14, 1948 2,559,353 Fisch July 3, 1951 2,870,438Solheim J an. 20, 1959 2,936,448 Marholz May 10, 1960 3,084,217 Fiore etal Apr. 2, 1963 FOREIGN PATENTS 792,478 Great Britain Mar. 26, 1958

1. AN IMPLOSION GUARD FOR A CATHODE RAY TUBE INCLUDING IN COMBINATION, ATRANSPARENT PANEL FOR COVERING THE VIEWING FACE OF THE TUBE, A MOUNTINGGASKET OF COMPRESSIBLE MATERIAL SURROUNDING THE PERIPHERY OF SAID PANEL,SAID GASKET HAVING A CHANNEL FORMED THEREIN TO RECEIVE THE EDGE OF SAIDPANEL, A STRUCTURE FOR SUPPORTING THE TUBE IN VIEWING POSITION, AFLEXIBLE FRAME ENGAGING SAID GASKET, FIRST MEANS RIGIDLY MOUNTING SAIDFRAME AT BOTH SIDES THEREOF TO SAID STRUCTURE, AND SECOND MEANSRESILIENTLY MOUNTING SAID FRAME AT THE TOP AND BOTTOM THEREOF TO SAIDSTRUCTURE SO THAT SAID GASKET IS PRESSED AGAINST THE VIEWING FACE OF THETUBE, THEREBY SUSPENDING SAID PANEL A SHORT DISTANCE IN FRONT OF THEVIEWING FACE OF THE TUBE TO SEAL THE REGION BETWEEN SAID FACE AND SAIDPANEL FROM FOREIGN MATTER AND TO FORM A RESILIENT GUARD FOR ABSORBINGIMPLOSION FORCES.